I'm torn on this one. The main utility of jQuery.sub is for plugins, which makes converting it into a plugin of its own pointless. It's not much code to insert into a plugin, but on the other hand it dives pretty deep into partially undocumented internals, and asking plugin authors to copy in that block of code means not only redundancy but also missing out on things like a fix to #11662.

I was excited for the introduction of jQuery.sub, and think I'd like to try saving it.